Refrigerating apparatus



June 8, 1943. MQRMAK 2,321,151

REFRIGERATING APPARATUS Filed March 26, 1941 2 Sheets-Sheet 2 w 4% ZINVENTORU .BYg

Patented June 8 1943 UNITED. STATES. PATENT OFFICE 2,321,151 REFRIGERATING APPARATUS Alex A. McCormack, Dayton, Ohio, assignor to General Motors Corporation, Dayton, corporation of Delaware Ohio, a

Application March 26, 1941, Serial No. 385,294 Claims. (01. 62-115) This invention relates to refrigerating apparaunloader.

Further objects and advantages of the present invention will be apparent from the following de- I scription, reference being bad to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings:

Fig. 1 is a sectional view partly diagrammatic showing my invention applied to a compressor;

Fig. 2 is an enlarged view of the unloader unit;

Fig. 3 is a sectional view taken on the line 3--3 of Fig. 2; and

Fig.4 shows a refrigerating system equipped with an unloader constructed in accordance with my invention.

It is recognized that it is old to use centrifugal unloaders and that many patents have been granted on various types of unloaders. However.

the prior art centrifugal unloaders have not been 7 fully satisfactory for various reasons.

For purpose of illustration, I have shown my invention applied to a four-vane rotary compressor unit. Reference numeral lll designates generally a sealed motor-compreSsor-condenser unit connected in refrigerant flow relationship with an evaporator 28 The unit l0 comprises a conventional motor having a stator l2 and a rotor II. The rotor H which operates a conventional four-vane rotor Hi. The rotor l8 operates within a conventional compressor cylinder 20. The shaft l6 is-journailed in a main hearing 22 which is formed integrally with the main sup rting frame 24. The compressor is provided with an inlet 26 connected is mounted on a shaft l8- which discharges the compressed gas into the motor-compressor compartment 32 in accordance with standard practice. The compressed gas discharged into the chamber 32 is condensed when coming in contact with the water coils 34.

Water is supplied to the coil 34 through the water feed line 36 and leaves through the line 38. The flow of water through the coil ,34 is con trolled by a conventional type of pressure operated valve 40 arranged in the line 38 and provided with line 42 which connects the pressure chamber of the valve 40 with the chamber 32 in accordance with well-known practice.

to the vapor 1ine'30 which-communicates with the refrigerant evaporator 28.. The flow of refrigerant to the evaporator 28 is. controlled by a conventional fixed restrictor 29 provided in thev liquid line 3|. evaporator 28. v I a conventional compressor A fan circulates air over the The compressor is provided with outlet (not shown) The compressor chamber 46 contains a supply of lubricant 44 which is subjected to the high side pressure. Lubricant is supplied to the main compressor bearing through the bore -48 provided Iin'the lower end of the main shaft Hi. The bore 48 communicates with a radial passage 50 which supplies lubricant to the lower end of the bearing 22 and to the upper end of I the bearing via the passage 52 provided in the bearingitself. The central portion of the main bearing 22 is recessed as shown at 54. A passage 56 connects the recess 54 with themain compressor inlet. A shaft seal 51. which may be of any conventionalconstruction prevents the escape of. lubricant from theupper'end of the main shaft bearing 22, as shown in Fig. 1. It is apparent,'threfore, that the pressure within the chamber 54 is substantially equal to the suction pressure or the low side pressure. Inasmuch as the main body of lubricant 44 is subjected to the discharge pressure or the high side pressure, there is a definite tendency for the lubricant supplied to the end portions of the main bearing 22 to flow towards the low pressure cavity 54 at the center of the bearing. Thus, the difference in pressure between the high and the low sides of the system forces the lubricant to the bearing surfaces.

A very simple centrifugal unloader may be added in a compressor of this type merely by boring out the upper end of the shaft It as shown at 60 and mounting a centrifug'ally operated valve unit 62 in the upper end of the vbore 60. The lower end of the bore 60 communicates with a radial passage 64 which in turn communicates with the low pressure compression chamber. through the recess 54 andthe passage 56. The centrifugal unloading "unit 62 comprises a cap V screw 66 having a central passage 68 extending from the, lower end of the screw to the radial passage 10 adjacent the head 14 (see Fig. 2). A flattened surface 12 is provided adjacent the outer end of the radial passage I0 and serves as a' valve seat, as shown in-Fig. 3. A washer 16' is secured to the upper end of the bolt. The washer 16 carries a pivot pin 18 on which is pivotally mounted a bell crank 80. The arm 82 of the bell crank 80 is larger and heavier than the arm 83. The arm 83 carries a neoprene valve member 84'' which cooperates with the port or passage 10. A spring 86 biases the bell crank 8|! into valve opening position so that in the absence of any centrifugal force opposing the force of the sp ing 86, the valve 84 remains in the open position, whereby the high pressure chamber 32 communicates with the compression chamber through the passages 10, 80; 64, 54 and 56.

Upon energization of the compressor motor, the heavier end 82 of the bell crank 80 tends to swing away from the center of rotation of the shaft I6 and overcomes the force of the spring 86 so as to automatically close the valve 84. As shown in Figs 2 and 3, the one end 90 of the spring 86 rests against the outer periphery of the disk 16 and the other end 92 engages the V aperture 84 in the bell crank III. The cap screw 6 also serves to fasten the motor-rotor I4 to the shaft IS. A pair of washers 96 and 98 have been provided as shown in Figs. 1 and 2. The

large washer 86 engages the upper surface of the motor-rotor H. The washer 88 is a conventional lock-nut washer which serves to prevent the cap screw 86 from becoming loose.

One big advantage of theunloader unit 62 is .that it may be tested prior tomounting in the compressor unit. By mounting the unit 62 on a might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. In a refrigerating system having a high pressure portion and a low pressure portion, a compressor comprising a shaft;-means for supplying lubricant to said shaft including a lubricant passage having one portion in communication with the low pressure portion of' said system, a centrifugal unloader carried by said shaft having means for equalizing the pressure between the high pressure portion of said system and the low pressure portion of said system, said unloader utilizing said one portion of said lubricant passage as an unloading passage. i

2. Refrigerating apparatus comprising a .casing, a compressor within said casing, a compressor operating shaft having a compressor unloadin passage provided therein, a valve assembly r movably mounted on said shaft as a unit and having a valve port communicating with said passage, said unit including valve means controlling the flow of fluid through said port and means responsive to the speed of said shaft for operating said valve means.

3. A centrifugal unloading device for a compressor unit having an unloading passage formed in the compressor operating shaft comprising in combination, means removably secured to said shaft as a unit including a member having a passage communicating with said unloading passage, a valve carried by said member for opening and closing the passage in said member, and means carried by said member responsive to the speed of said compressor for opening and closing said valve. 4. In combination, a rotatable shaft having a fluid passage therein, a fluid flow control unit removably secured to said shaft and having a valve port communicating with said passage, said unit including valve means controlling the flowof fluid through said port and means responsive to the speed of said shaft for operating said valve means.

5. In combination, a compressor, a compressor casing forming a lubricant sump, an inlet port for said compressor, an outlet port for said compressor through which compressed gas is discharged into said casing, means for supplying lubricant from said sump to, said compressor comprising a lubricant passage, means whereby one portion of said passage communicates with said inlet port, said shaft having an axial bore. communicating with one portion of said lubricant passage, a valve assembly removably secured to said shaft as a unit, said assembly having a passage communicating with said bore and with the interior of said casing and having means responsive to changes in the speed of said shaft for closing said passage at high speeds and opening said passage at low speeds. 

